Molded products formed from acrylic resins have excellent transparency, and have beautiful external appearance and weather resistance, and therefore, these molded products are widely used for applications such as electronic components, automotive parts, optical components, decorations, and sign boards. Particularly, acrylic resin molded products formed from acrylic resin compositions containing rubber-containing polymers are widely utilized.
Such rubber-containing polymers are produced by, for example, an emulsion polymerization method. Specifically, a polybutadiene latex, a styrene-butadiene copolymer latex, a styrene-butadiene-acrylonitrile copolymer latex, and an acryl rubber latex are produced by emulsion polymerization methods. Then, each of these latexes is subjected to a treatment of salting out, acid solidification, spray drying, or freeze-drying, and thereby a polymer in a powder form is separated and collected. To this polymer in a powder form, usually, compounding agents are appropriately added. The polymer having compounding agents added thereto is melt-kneaded with a single-screw extruder, a twin-screw extruder or the like, and is extruded as strands, which are then cut by a cold cutting method or a hot cutting method and pelletized. Subsequently, these pellets are supplied to a molding machine and processed into acrylic resin molded products.
Film-like acrylic resin molded products (hereinafter, also referred to as “acrylic resin films”) have a feature of having excellent transparency, weather resistance, flexibility and processability. In the light of utilizing this feature, acrylic resin films are laminated on the surfaces of various resin molded articles, wood products, and metal molded articles.
Patent Document 1 proposes, in relation to the production of an optical film by stretching between rolls, a method for producing a smooth film that has no rupture of the film caused by fusion to heated rolls, no terraced planar defects (level unevenness), or no stretch unevenness.
Patent Document 2 proposes a film having improved blocking properties and slip properties with deteriorating transparency, which is obtainable by adding, to a transparent synthetic resin as a base, finely powdered glass having a refractive index that has been adjusted to match the refractive index of the base synthetic resin.
Patent Document 3 proposes an acrylic resin film having excellent external appearance, in which the density of foreign materials is 1 piece/m2 or less.